초록 ▼

An improved process and apparatus for pH control and energy savings in chlor-alkali electrolysis cells is disclosed wherein a fuel cell type spaced porous catalytic anode is utilized to chemically oxidize a controlled, sub stoichiometric amount of hydrogen to provide hydrogen ions to a recirculating

An improved process and apparatus for pH control and energy savings in chlor-alkali electrolysis cells is disclosed wherein a fuel cell type spaced porous catalytic anode is utilized to chemically oxidize a controlled, sub stoichiometric amount of hydrogen to provide hydrogen ions to a recirculating anolyte. The pH is monitored and the flow of hydrogen fuel adjusted to provide a resultant desired pH in the range of about 2 to about 4. Optionally, hydrogen gas produced at the cell cathode may comprise the fuel supply and a spaced porous catalytic cathode may be employed for hydrogen supply control and depolarization.

대표청구항 ▼

In the process for manufacturing caustic and chlorine which comprises recycling as an anolyte feed solution a substantially saturated aqueous alkali metal chloride solution into the anode compartment of a cell, said cell having an anode compartment containing an anode, a cathode compartment containi

In the process for manufacturing caustic and chlorine which comprises recycling as an anolyte feed solution a substantially saturated aqueous alkali metal chloride solution into the anode compartment of a cell, said cell having an anode compartment containing an anode, a cathode compartment containing a cathode which is catalytic for the reduction of oxygen and a substantially fluid impermeable, cation permselective fluorocarbon membrane separating said anode and cathode compartments, passing a direct electric current between said anode and said cathode and recovering elemental chlorine from said anode compartment substantially equivalent chemically to the alkali recovered from said cathode compartment, the improvement which comprises: (a) contacting said cathode with a quantity of a substantially carbon dioxide free gas selected from the group consisting of oxygen, air and mixtures thereof, which quantity is substantially more than that chemically equivalent to the amount of direct current passed; (b) maintaining the liquid immediately effluent from said cathode compartment at a concentration of at least about 8 percent by weight and at a temperature of at least about 70°C. thereby readily causing said gas to react with water at said catalytic cathode to produce hydroxide ions and to substantially completely inhibit the formation of hydrogen gas at the cathode; (c) recovering at least about 90 percent of the liquid effluent from said anode compartment and adding water and alkali chloride salt to produce a substantially saturated brine solution; (d) adjusting the concentration of any non-monovalent metallic cation in said saturated brine solution to a concentration of not more than about 5 parts per million thereby producing said anolyte feed solution; (e) maintaining the pH of the liquid effluent from said anode compartment in the range of from about 2 to about 4 thereby controlling the formation of chlorate in the anode compartment.